Actually, I think it's not too difficult, but we need to make it easy. Instead of all the balls in one bag, we split them into 50 bags with 40 balls each. You then use an rng app to select a bag randomly to inspect and can see that says 51-100 has those numbers. As for number of balls, it can be determined with a scale since ball bearings have a rather precise weight.
Discussion
I didn't realize you were just numbering them, but obviously tiresome to actually verify.
The best method for this is still just printing out the words & cutting them up.
I do like SeedSigner's new offering as well.
Easy to verify & supports their project.